The present invention concerns antenna systems for receiving broadcast signals such as television signals.
Conventional indoor TV antenna systems generally include two separate antennas for respective VHF and UHF reception. The antenna for receiving the VHF bands employs a pair of telescopic elements forming a dipole with each of the elements having a maximum length of from 4 to 6 feet (1.5 to 2.5 m). The two elements usually are mounted to permit the elements to be spread apart to increase or shorten the dipole length and those elements are commonly referred to as xe2x80x9crabbit ears.xe2x80x9d The indoor UHF antenna typically is a loop having a diameter of about 7xc2xd inches (20 cm).
One problem associated with the conventional indoor antenna systems is that the physical dimension of the VHF dipole is undesirably long for the ordinary setting in a living room and that the length as well as the direction of the dipole elements may need to be adjusted depending upon the receiving channels. The second problem is that the performance of such conventional indoor VHF/UHF antennas changes in response to changes of the physical conditions around the antenna elements. For example, it is difficult for a user to make proper adjustment of the antennas since a human body coming into contact with an antenna changes the electro-magnetic conditions associated with the antenna elements. The third problem is that the conventional indoor antenna systems do not always provide a sufficient signal level for good reception.
A need exists for an antenna system including compact-size antennas which are capable of receiving a sufficient level of signals throughout the entire VHF/UHF broadcast bands of frequencies without any physical adjustments. Further, there is need for such an antenna system that can be used in either indoor or outdoor applications.
In accordance with the present invention, an antenna system for receiving VHF/UHF broadcast signals comprises a planar antenna and a tuner unit which includes a tuning arrangement. A gain controllable amplifier may be included in the tuner unit where necessary. The planar antenna includes a pair of antenna elements which are substantially identical in shape. These elements are located on the respective surfaces of a dielectric board. The tuning arrangement includes a plurality of matching networks for the respective plurality of bands of broadcast frequencies.